Risk of Legionella when storing water?

[TSN79]

Cold water is heated to 65°C so that Legionella is killed. If the water is then stored in a tank and allowed to cool down to room temperature, can it "magically" reappear or can the water be stored a while (maybe a week) without risk?

 

[SW VandeCarr]

Cold water is heated to 65°C so that Legionella is killed. If the water is then stored in a tank and allowed to cool down to room temperature, can it "magically" reappear or can the water be stored a while (maybe a week) without risk?

60-65C is the minimal sufficient temperature range to kill Legionella. Why do you feel you needed to treat this water in the first place? The biggest danger with contaminated water is that the microbe can be spread by aerosolization, typically by large central air conditioning systems. The water will not likely become recontaminated unless exposed to a potential source, which is why I ask the question.

Otherwise, if the water is free of the microbe and stored in a clean closed container in a cool place (at least under 20C, but the cooler the better), there should be no problem.

 

[TSN79]

Why do you feel you needed to treat this water in the first place?

Personally I don't, but ever since there was an outbreak of Legionnaires' disease (although it was traced back to a scrubber which isn't really a justifiable comparison imo) there's a bit of hysteria going around amongst people. I know that questions regarding it will come once the installation is done so I just thought I'd check if the initial heating would take care of it.